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Diffstat (limited to 'Documentation/bpf/ringbuf.rst')
| -rw-r--r-- | Documentation/bpf/ringbuf.rst | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/Documentation/bpf/ringbuf.rst b/Documentation/bpf/ringbuf.rst index 75f943f0009d..a99cd05d79d4 100644 --- a/Documentation/bpf/ringbuf.rst +++ b/Documentation/bpf/ringbuf.rst @@ -124,7 +124,7 @@ buffer. Currently 4 are supported: - ``BPF_RB_AVAIL_DATA`` returns amount of unconsumed data in ring buffer; - ``BPF_RB_RING_SIZE`` returns the size of ring buffer; -- ``BPF_RB_CONS_POS``/``BPF_RB_PROD_POS`` returns current logical possition +- ``BPF_RB_CONS_POS``/``BPF_RB_PROD_POS`` returns current logical position of consumer/producer, respectively. Returned values are momentarily snapshots of ring buffer state and could be @@ -146,7 +146,7 @@ Design and Implementation This reserve/commit schema allows a natural way for multiple producers, either on different CPUs or even on the same CPU/in the same BPF program, to reserve independent records and work with them without blocking other producers. This -means that if BPF program was interruped by another BPF program sharing the +means that if BPF program was interrupted by another BPF program sharing the same ring buffer, they will both get a record reserved (provided there is enough space left) and can work with it and submit it independently. This applies to NMI context as well, except that due to using a spinlock during @@ -182,9 +182,6 @@ in the order of reservations, but only after all previous records where already committed. It is thus possible for slow producers to temporarily hold off submitted records, that were reserved later. -Reservation/commit/consumer protocol is verified by litmus tests in -Documentation/litmus_tests/bpf-rb/_. - One interesting implementation bit, that significantly simplifies (and thus speeds up as well) implementation of both producers and consumers is how data area is mapped twice contiguously back-to-back in the virtual memory. This @@ -200,7 +197,7 @@ a self-pacing notifications of new data being availability. being available after commit only if consumer has already caught up right up to the record being committed. If not, consumer still has to catch up and thus will see new data anyways without needing an extra poll notification. -Benchmarks (see tools/testing/selftests/bpf/benchs/bench_ringbuf.c_) show that +Benchmarks (see tools/testing/selftests/bpf/benchs/bench_ringbufs.c) show that this allows to achieve a very high throughput without having to resort to tricks like "notify only every Nth sample", which are necessary with perf buffer. For extreme cases, when BPF program wants more manual control of |